Electrical starter motors are well known for starting internal combustion engines in automobiles and many other devices. The motors include an output shaft which is rotated when the electrical motor is energized. The end of the output shaft carries a drive pinion which engages and rotates a starter gear on the internal combustion engine to start the engine. The drive pinion is then disengaged from the starter gear on the engine when the engine is running.
Some devices which include electrical starter motors are operated in environments where double insulation is required or preferred to prevent the possibility of an electrical shock being given the operator. One such device of which Applicants are aware is a snowthrower having an internal combustion engine. Such snowthrowers are often sold with an electric starter motor attached thereto. The motor typically has a power cord which is plugged into an electrical socket whenever it is desired to start the snowthrower. A button is then pushed by the operator to energize the starter motor using the line voltage (110 V) contained in the socket.
The starter motors used on the snowthrowers with which Applicants are familiar have typically used a drive pinion made from plastic. This was necessary to provide the second level of insulation needed in double insulated starter motors, the first layer of insulation having been provided by the insulated windings of the motor itself. However, one disadvantage of plastic starter motor pinions is that they wear out quite quickly. This then requires that the pinion be replaced which is obviously undesirable.